Fine structure splitting of quantum dot excitons: Role of geometry and environment

We present the results of high resolution photoluminescence spectroscopy of single GaAs/AlGaAs quantum dots grown by droplet epitaxy technique. By measuring the line broadening and the linear polarization of the excitonic photoluminescence we get new insights on the role of extrinsic effects on the quantum dot symmetry. Taking advantage of the lack of strain in the GaAs/AlGaAs system we study the relationship between the geometrical elongation of the confining potential and the exciton fine structure splitting.